ChatGPT's reply: (For reference)A: The main reason lies in the chemical properties of nitrous acid itself and the limitations of electrochemical detection technology:
(1) Unstable redox reaction: The redox potential of nitrous acid is relatively unstable and it is easy to decompose or form by-products under electrochemical conditions. This will lead to inaccurate test results and place high demands on the selection and surface treatment of electrodes, increasing the technical difficulty.
(2) Insufficient sensitivity and selectivity: The concentration of nitrite in the environment is usually very low, so the detection system needs to be extremely sensitive. However, electrodes are easily interfered with when measuring low concentrations of nitrite, especially common interferents such as chloride ions and sulfate ions, which can affect the accuracy of the measurement and cause errors.
(3) The electrode surface is easily contaminated or poisoned: In the solution, nitrous acid may react with the electrode surface to form deposits or by-products, further reducing the sensitivity and stability of the electrode, making the electrode easily "poisoned", which also affects the reusability of the electrode.
(4) Cost and life issues: Compared with colorimetry, the design and manufacture of electrodes are more complicated. The cost of electrode materials is high, and the life of electrodes is relatively short. Colorimetric methods are generally cheaper, more convenient, and have better stability and repeatability in on-site testing.
For these reasons, the detection of nitrite currently mostly adopts the drop colorimetric method, because this method is simple and easy, has low equipment cost, less interference, and is widely used in environmental testing and food safety. Although electrode-based detection has the potential to provide rapid and instantaneous detection, the above-mentioned technical challenges still need to be overcome to achieve reliable nitrite detection electrodes.
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